Really happy with the extension, it does what it says. Many thanks to its developer.

I installed this add-on to copy a bit of text from
http://koufukuji.yokohama/analects/764
I thought at first that I had failed (and gave a two star review) because as well as prevent copying, the site changes the selected text highlight colour to a very pale yellow. This add-on works and allows me to copy text from the above page, but it would be even better if it changed the highlight colour to one which I can see for easier selection.

Absolute Winner between all of similar addons! It works even on mobile FF for Android! (but I had to request desktop version of the site, to be able to install it). Thanks a lot!

Excelente! Me ajudou muito na Faculdade que faço bloquearam o uso do botão direito do mouse no portal! Um abuso!

It's good but the "Absolute Mode" enabled messes with the search perameter on sites like movieninja.io.